ECG finding most associated with STEMI?

• A. ST segment depression
• B. ST segment elevation
• C. Peaked T waves
• D. Prolonged QT

Answer: (B)

ST-segment elevation on an ECG is the hallmark sign of STEMI because it shows acute transmural (full-thickness) injury to the heart muscle from a sudden coronary artery occlusion. The injured area creates a current of injury that shifts the baseline during the ST segment, producing elevation in the leads that overlie the affected region. This elevation can be accompanied by reciprocal ST depression in opposite leads and may resolve with successful reperfusion.

Other patterns reflect different situations: ST-segment depression is more typical of subendocardial ischemia or NSTEMI; peaked T waves can occur with early ischemia or electrolyte disturbances like hyperkalemia; and a prolonged QT is seen with electrolyte issues, drugs, or congenital conditions—not the classic sign of an acute STEMI. In practice, recognizing ST elevation signals an emergency requiring urgent reperfusion therapy to save heart muscle.